drm/arcpgu: fix device node leak

This function gets a device_node reference via
of_graph_get_remote_port_parent() and stores it in encoder_node, but never
puts that reference. Add it.

There used to be a of_node_put(encoder_node) but it has been removed by
mistake during a rework in commit 3ea66a7 ("drm/arc: Inline
arcpgu_drm_hdmi_init").

Fixes: 3ea66a7 ("drm/arc: Inline arcpgu_drm_hdmi_init")
Cc: stable@vger.kernel.org
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://patch.msgid.link/20260402-drm-arcgpu-fix-device-node-leak-v2-1-d773cf754ae5@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

Author: lucaceresoli

drivers/gpu/drm/tiny/arcpgu.c

@@ -250,7 +250,8 @@ DEFINE_DRM_GEM_DMA_FOPS(arcpgu_drm_ops);
 static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
 {
 	struct platform_device *pdev = to_platform_device(arcpgu->drm.dev);
-	struct device_node *encoder_node = NULL, *endpoint_node = NULL;
+	struct device_node *encoder_node __free(device_node) = NULL;
+	struct device_node *endpoint_node = NULL;
 	struct drm_connector *connector = NULL;
 	struct drm_device *drm = &arcpgu->drm;
 	int ret;